Conventionally, there is provided a remote monitoring control system in which a transmission processing device, an operation terminal device and a control terminal device are connected by two signal lines (see, e.g., Japanese Unexamined Patent Application Publication No. 2001-86577). In the remote monitoring control system, specific addresses are respectively allotted to the operation terminal device and the control terminal device.
The operation terminal device includes a plurality of switches. As the states of the switches are changed, e.g., by pressing the switches, the operation terminal device transmits the information as operation data to the transmission processing device.
The transmission processing device gains access to each of the operation terminal device and the control terminal device and receives operation data from the operation terminal device. Furthermore, the transmission processing device transmits control data to the control terminal device which is previously associated, by an address, with the operation terminal device that has generated the operation data.
The control terminal device includes relays provided therein. Upon receiving the control data from the transmission processing device, the control terminal device turns on or off the relays, thereby controlling loads.
Each of the operation terminal device and the control terminal device (hereinafter abbreviated as “terminal device”) includes, e.g., a transceiver circuit unit for transmitting and receiving a transmission signal or the like, a terminal processing unit for, e.g., monitoring the operation states of the switches and executing control of the relays, and a synthetic-resin-made device housing, and so forth. The terminal processing unit and the transceiver circuit unit are realized by, e.g., mounting an integrated circuit on a printed wiring board.
The device housing is composed of a synthetic resin molded body having a rectangular box-like shape and is configured to accommodate the printed wiring board therein. The device housing includes a pair of terminal attachment parts provided in the rear side wall (or the rear wall) thereof. Each of the terminal attachment parts includes two attachment holes into which signal line terminals are inserted, and a cylindrical depressed portion provided between the two attachment holes and provided with a bottom. The terminals are so-called screw terminals. Each of the terminals includes a terminal plate and a terminal screw.
The terminal plate includes a rectangular main portion and a pair of leg portions. One of the leg portions (a first leg portion) is electrically connected to a circuit of the printed wiring board through, e.g., a lead wire. The other leg portion (a second leg portion) is used to fix the terminal to the device housing and is formed short so as not to interfere with the printed wiring board. In this case, it is desirable that the lead wire is formed to have a necessary minimum length required in interconnecting a specified portion of the printed wiring board and the first leg portion. If the second leg portion is inserted into the attachment hole corresponding to the first leg portion (a first attachment hole) and if the first leg portion is inserted into the attachment hole corresponding to the second leg portion (a second attachment hole), there is a possibility that the length of the lead wire is insufficient. If the length of the lead wire is prolonged, time and effort are taken in dealing with the extra length of the lead wire.
That is to say, it is desirable that the first leg portion is inserted into the first attachment hole while the second leg portion is inserted into the second attachment hole.
In the conventional example, the main portion of the terminal plate is formed to have a line symmetry shape with respect to a straight line which passes through the midpoints of the sides connected to the leg portions. Thus, the terminal plate can be attached to the device housing even in a 180 degree rotated state. In the conventional example, there is a possibility that, during assembly, the terminal plate is reversely attached to the device housing by a worker. If the terminal plate is reversely attached, it becomes difficult to electrically interconnect the terminal plate and the printed wiring board.